Field of the Invention
This invention generally relates to semiconductor technology, and more particularly to a semiconductor device having super-junction structures and fabrication thereof.
Description of the Related Art
Most conventional vertical diffused metal-oxide semiconductor field-effect transistors (VDSNOFETs) use an n-type epitaxial drift region and a p-typed based doping region thereon to form a p-n junction for withstanding the applied voltage. When increasing the operating voltage of the semiconductor device, the doping concentration of the n-type epitaxial drift region must be decreased, and hence thickness thereof must be increased. Since on-resistance (Ron) is limited by the doping concentration and thickness of the n-type epitaxial drift region, this way of increasing the withstand voltage of a p-n junction increases on-resistance. A diffused metal-oxide semiconductor field-effect transistor with a super-junction structure is capable of improving Ron and withstanding high break-down voltages.
The column-shaped n-type doping region and the p-typed doping region formed by ion-implantation are employed to achieve charge balance, such that the device is capable of withstanding high voltage. However, the method using the column-shaped n-type doping region and the p-typed doping region is limited by the maximum depth of ion implantation after performing thermal diffusion. Therefore, the area for current to pass through is also limited. The size of the device must be increased in order to increase the total surface area of the n-type doping region and the p-typed doping region.
Accordingly, a semiconductor device with a super-junction structure and fabrication thereof is required to address the issues of the conventional technology.